The present invention relates to apparatus for diverting a communications path from a wire pair extending between two locations to an alternate wire pair extending between the same locations so that repair work such as splicing may be accomplished on the bypassed pair without interruption of, or interference with, the communications circuit.
In communications systems, and particularly in telephone carrier communications systems, multiconductor cables provide the signal paths forming the intercommunication network. Typically these cables are placed in underground conduits, are suspended aerially, or are directly buried in the soil. Regardless of the manner of installation, these cables tend to fail from time to time due to a variety of factors, such as exposure to moisture and moisture-induced electrolysis, exposure to chemicals which attack the insulation, exposure to fire, mechanical vibration, and to attack by rodents and other living things. Consequently, the cables must be repaired or replaced from time to time.
In telephone systems, the standard procedure followed heretofore has been removing the pair to be spliced or replaced from active service by appropriate bypass patching at terminal ends to transfer the circuit in question to another pair, accomplishing required testing, cutting, and splicing, checking the continuity of the repaired or replaced cable, and then returning the communications circuit to the original pair by removing the bypass patches at the terminal ends. This procedure has required the attention of at least four technicians: two at the terminal locations to accomplish the patching, and two at the ends of the cable section to be cut, spliced and returned to service.
Although test apparatus and techniques have been available to reroute temporarily a communications circuit away from a section of the cable to be cut and spliced so that uninterrupted communications service has been provided, the apparatus and techniques have not provided a fail-safe guard circuit ensuring that communications service will not be interrupted as a result of incorrect cutting and splicing procedures. Because of this omission, the apparatus has typically been frequently misconnected to the lines so that when they are cut, communications service is lost, with resultant loss of revenue and customer complaints to the communications or telephone utility. Such apparatus and techniques have proved to be particularly troublesome with respect to signal repeaters in carrier systems which have masked some test signals of the apparatus of the prior art by amplification of crosstalk, etc., so that verification of a true metallic bypass connection to the section to be cut and spliced has been difficult to accomplish.
The foregoing drawbacks, as well as others, are overcome by the present invention which will now be described.